Photograph of EIFS synthetic stucco building interior. Stucco Over High-R Foam Insulating Board

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This article discusses the installation of stucco exterior wall finishes over insulating foam board, including the choice of high-R value insulating board for use under stucco on building exteriors.

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Stuccoing over High-R Foam Board Insulation

Accompanying text is reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.

Readers should see STUCCO WALL METHODS & INSTALLATION, and also SIDING EIFS & STUCCO and STUCCO PAINT FAILURES and also may want to review POLYISOCYANURATE FOAM INSULATION. Contact us to suggest text changes and additions and, if you wish, to receive online listing and credit for that contribution.

This question-and-answer article about the choices of insulating foam board for use under stucco exterior finish on buildings, appears in full-text just below and quotes-from, updates, and comments an original article from Solar Age Magazine and written by Steven Bliss.

Question: "In-Town Solar Condos: One Developers's Plan Book" (Solar Age, 9/83) includes mention of an exterior insulation system for masonry walls using 2-inch urethane under stucco.

I have had little success locating such a system in Phoenix that uses polyurethane and not polystyrene foam insulating board on the building exterior.

Can you supply me with information on a polyurethane insulation system or any other exterior insulation that might give me a better R-value than 2-inch polystyrene foam insulating board? - James Hoffman, Tempe, AZ.

Answer: First, a clarification - strictly speaking the rigid foam insulating board used in the La Vereda Compound (the subject of the article) was a foil-faced polyisocyanurate foam insulating board (Thermax™), not a polyurethane.

Ann MacKinnon, office manager of LaVereda developer Communico, said that The company often used Thermax™ over concrete block walls and under stucco on buildings, as do most builders in the Santa Fe area.

Wire stucco lath is placed over the foam insulating board and attached to the masonry below using concrete nails. MacKinnon said that "a builder Santa Fe who didn't know and use this technique would probably be out of business" because demand is high for adobe-like finishes. She added that lath and stucco can be used over sprayed-on urethane foam insulation as well.

Readers should also see SIDING EIFS & STUCCO and also may want to review POLYISOCYANURATE FOAM INSULATION.

Original article:

Here we include solar energy, solar heating, solar hot water, and related building energy efficiency improvement articles reprinted/adapted/excerpted with permission from Solar Age Magazine - editor Steven Bliss.


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